Elimination of tricords in toll exchanges



Sept 25, 1951 l A. J. HENQUET ET AL 2,568,733

ELIMINATION OF TRICORDS IN TOLL EXCHANGES Filed May 25, 1947 4 2Sheets-Sheet 1 MRL sept. 25, 195`1 A. J. Hr-:NQUET ETAL 2,568,733

ELIMINATION oF TRIcoRDs IN TOLL EXCHANGES 2 sheets-sheer 2 Filed May 25,1947 NVENT s ANDRE'JEAN EQUET Mcl-:L ROGER MAUGE wr B lo Patented Sept.25, r1951 ELIMINATION oF 'rRIooRDs 1N 'roL Y EXCHANGES Y Andre JeanHenquet and Roger Marcel Mauge,

' Boulogne-Billancourt, France, assignors to International StandardElectric Corp., New York, N. Y., a corporation of Delaware ApplicationMay 23, 1947, Serial No. 750,124

In France September 22, 1943 section 1, Public Law 690,Augst s, 194sPatent expires September 22, 1963AV This invention relates to new anduseful improvements in the circuits disclosed in our c-vv pendingapplication iiled July 23, 1947, Serial No. 763,062, which will be setYforth in detail .with reference to the attached drawings, in which;

(Fig. 1 shows the general scheme for establishing communication betweentwo .first-class trunks in exchanges employing features of theinvention:

.'Fig. 2 shows the portion of a rst-class trunk,

incoming orA outgoing, required for explaining the operation of toilexchanges incorporating fea-V tures of the invention;

Fig. 3 shows a portion ofthe cord circuit useful in explaining theinvention; and Y Fig. 4 shows an example of a four-wire connecting ordiversion circuit to link iirst-class trunks to each other, according tothe invention. According to the invention a plurality of cord circuitsare provided at anv operators position. These cords, by means ofdetachable connectors, serve as links between calling and vcalled trunksterminating at the position. Also provided at the operators position area plurality of diversion or by-pass circuits each terminating in a pairof finders connected inmultiple to the trunks. A diversion or by-passcircuit is employed whenever two rst-class trunks are to be connected toone another and when connectedto the two trunks by-passes the operatorsposition. By means of a diversion circuit additional equipment may beconnected to the talkingconnection and a circuit.

is provided over which signals necessary for linkingvtwo rst-classtrunks may .betransmitted In the embodimentshown, the iirst-class trunksare characterized by a third wire. over which a positive potential isapplied. l

In Fig. 1, the general scheme for first-class trunk connections is shownto comprise a double cord I having connectors, such as plugs l2 and 3Vand jacks, 4 and 5 at an operators position. FindersV 6 and 'I areprovided for iinding calling and called rst-class trunks. They areconnected over circuits 8 and 9 so that either iinder may connect thediversion circuit I0 irrespective of the calling or called condition ofthe trunk.

When it is desired to connect a first-class calling trunk to a.rst-classcalled trunk, alternating calling current is sent over 'wiresII and I2 to operate relay I3, which is bridged across the line overback contacts of relay I4.' When relay I3 operates, it extinguishes thefree-line lamps I and I6, and by a front contact lights calling lamp I1.

The operator plugs into jack 4 with plug 2, thereby connecting her cordcircuit (Fig. 3). I f

5 Claims. (C1. 179-27) Y tricail isjtq a'rstfcnss trunk, identine'd ylikeY the calling` trunk, by positive potential on wire: I8, relay s l9,282I, 22 and 23 (Fig.'3) operate when ythe called trunk isplugg'ed in.Relay .24'

. isoperated over the iront contacts of relays and 2 Land connec'tsrelay2|] to the negative bat-V tery instead of Y to y ground. Thissubstitution causes thepulling-up of relay 25 of the'calling' trunk(Fig. j2,) which operates only on the strong current obtained when thepositive Vand negative batteriesare in series. vThe front left contactof relay 25 voperates relay 26, which locks, applies a test potentialover wire 21 and, over the back contact of relay/28, connectsgroundtowireA 29. Relay l26 Yoperates starting relay 3l)v over wirel 29vof the diversion circuit (Fig. 4)," which then closes a circuit for allthe free diversion circuits, i.e. all those whose sequence switch V3I isin posi-V tion l or 10, whose jack 32 is closed and whose` alarm relay33 is der-enengized.` 'lhe front'contact of relayV 304operates relay 34(jack 32 andback' contact of relay y33) ,which heats the cathodeA oftube 35. .The primary of a gridtransformer '36 of tubev 3511s connectedto a source of phonic current (40,0 cycles) over front contact of relay34 andlowerrcontacts of cam 3l. Relay 38y in series in thetubeplate,voperates and actuates relay 39' (left-hand contactsV cam .740,relay 39, upperright and lower left contactscam 4I, battery). If thetubedoes'not operate, relayY 38 remains at rest, and relay 33, which isslow operating, has time to operate:v battery, relay 33, lower right andleft contacts cam 42, front corn tact of relay 34, Yback contact ofrelay 38,'ground. Y The front vcontact of relay 39 applies ground 'tolthe high resistance Winding of relay 59 (ground, upper right and leftcontacts cam 43, relay 59) and also operates iinder magnet 6 overback,contact ofrelay 59, frontcontact of` relay 39 and lower right andleft cam 44, Y A

The wipers of `iinder 6 rotate and select the callingtrunk. Relay 59 ofthe first diversion circuit finding the calling trunk (characterized-bythe potential applied to wire 2I)V operates (upper right and lower leftcam 46, high resistance winding of relay 5,9, upper contacts of camr43,front contact vof relay 39 to ground), stops iinder 6 and closes acircuit for itslow resistance winding in series with relay 45 over cams4l and 48. Relay 45 operates whenthe test is successfully complet# edandrcauses the sequence switch 3I to advance froml to 3 (battery,driving magnet 3l, upper right cam 49, upper right cam 50, front contactrelay 4 5, back contact relay 33, ground). As soon as position 1 ispassed the'ii'nder 6 stops. Relay thesame order in their banks.

aceeps 38 falls back because tube 35 stops operating, the phonic currentsupply of the primary of its grid transformernis cut off at cam 31.After position 3/4, relay 34' is held independently of the startingrelay over the back contact of relay 33. Bef sides, relay 45 isconnected to Wire 5l (upper left and lower right of cam 41) and tog'roi'ind'Kupper'l contacts of cam 48, front contact relay 45). Wipe"ers 52 and 53 are connected togethenover ,wires 21 and 5I and frontcontact or relay 2 6, whereby the test potential is reduced -to prevent'theoperation of another relay 59. g, ,Y

In position 2, a ground across a {LOGO-ohm resistance 54 (Fig. 4) isconnected over lower right and upper left contacts of cam"4`l, wiper 55,Wire 54, relay 28 to battery The armature of relay 2B disconnects groundfrom wire 29 which de-energizes relay 30. Y,

In position 3, relay 594 which is disconnected from wiper@ in roite'n11/2 Scam 46). is 0011-. ncctedwto wiper 5610i under-1 oyerflwer'conf'tacfcsxof cam 46. The clutch magnet of l'fnder 1 'ispofnnected vto theback contact of relay 59 over-,therlower contacts of cam 51v and starts:

Wheniinder 'lhleaves its rest position, it causes Sequence switchltowadvan'ce from 3 vtofl by applying ground vfrom oir-normal ccntact 58ordnen. ,lower renfrew @new ,om wand' upper right-hand contact of cam49'. VFirider 1 Continues@ hunt f l, Innpos'ition il, the primary oftransformer 3,6 connectedjover f ront contact 'f relay 34, carri 6l towiper 62,of `vfinderV 6 andthence'fover wire la, sieeyeqf jack@ anu p'lg2, r'e1ay24f front, condenser 3, sleeve vof plug 3 and jack 5 o'f Ythecausa trunk piuggedin ny' the operator'.

When i"inderfY rcaches the set of contacts' corresponding totherstfclass: trunk plugged`r in by tlieoperator, the source of phiccurrent is con-'- nected, over wire I8Y of Ythis trunk Vand wiper' 6 6andjtllus vto thepriinary Avifiiiding of trans Y Y, .,frubelss and thenfiay sa` again operate and connect aA ground t're'lay 59 (frontcontact-of relay 38,lower and upper left con;

ta tsgcams, reiayje). 1f `fun potential lis roundy I bywiper 56,re lay5`9 operates,V stops under 1 andV causes 1the sequence switch 3|V toladvance from position l to position 6.

fI It 4is 'to be Anoted that the relative positions of theA trunksin thender banks are immaterial and'thecalling trunk may be ahead ofthe calledtrunk," In this case, when finder 1 passes over thecontacts of thecalling' trunk, relay 36` (Fig. si wur operate, but relay. 59cannotjoeerate ne: cause the potential foundby wiper 5,6 on Wire 5I Visreduced byrelay 45 connected to the wire Stover 52 of Afinder 6.v crumayunrewise happen that Aander 1 might test a circuit intended forseizure by another finder., Wrong connections Vare,impossible becausethewtwo finders 1 start from the same normal positron and the circuitsare arranged in In position `5 l ofthe sequenceswitch, relay 59 fallsoff and ground connected to wiperl 56 ofY under 1Y over lowcr right andupper left contacts of cam 4,6 toguarl the Ydiversion circuit. In posi;tion V6 relay 39 is connected over its two windings in series towiper 64of finder 1 (wiper 64, lower iight and upper left contacts cam65,'Wiiidi`ngs relay 39, upperycontacts of cam 46, ground), wherebyrelays 28 and 66k (Fig. V2) of the called ',rstl'class trunkpperate(battery, relay 28, and relay 66 inparallel; wiper 54, wiper 64, lowerright and upper left contacts cam 65, relay 39, upper contacts of cam40, ground). Relay 39, which is marginal, operates and advances thesequence switch from position 6 to position 7. Theground across the4,000-ohm resistance 54 connected over the lower right and upper left ofcam 4I and Wiper 55 to wire 54 is replaced by the low 'resistanceWin'dingof relay 39, which is held in series with relay 66 (Fig. 2) ofthe calling firstclass trunk.

A front contact of relay 66 (Fig. 2) operates relay 61, which'eliminates attenuation coil 68. and another frcnt contact of relay 66connects a Vbattery across {LOGO-ohm resistance 69 to signaling wire 10,which changes terminal box 1I from four-wire to two-wire connection.

when the operator depresses listening key 12 (Fig- 3) relay 13 isconnected vby wire 14 to battery across a 50G-ohm resistance 15. Relay13 operates and causes relay 16 to operate. Front contacts of relay 16connect in the operators head set over Wires 19, 8|J.y Relay 8| operatesover front contact of relay 16, wires 82, 83, front-V contactof relay 13and front contact of relayZZ, underthe control of Vseparation key at theoper-i ators position.

If the Ykey 84 is operated, relay 8l falls back andA batteryVVisiconnectedacross 50G-ohm resiste ance 85, wire 86 vand frontcontact ofrelay'16,:to relay 81, which is thereby energized.- Relay 81disconnects` the negative battery from wire I8.;

hence relay 25 of the calling trunkA (Fig.2) isreleased and relay 66also releases thereby reintroducing coil 68' and four-wire terminalbox'H.

The conversation,- when going from vleft to? right, takes place; overVwires I'l, I2 (Fig. 2), front contact o'f relay 61, wires96, 91 (Fig.4), wipers 86, 89 of finder 6'; front contacts relay |66 'and'v wipers94j and 95 ofnders 1; when Agoing from right to left, then over wipers92; 93 front contacts of relay |60, wipers 90, 9i and Wires 98; 99.-Relay |00 is energized in positions 7 and 16 of the sequence switch fromground at relay 5,9-,- front contact relay 39,'rightconta'cts of cam44,.= When theV operator pulls out plug 2, all the' elements return totheir normal position^ andVv vwhen relay 45 falls :oft the sequenceswitch. 3l"

circuit over cam 49 lower left .which moves the sequencey switch from 9into 10, whereupon 39 energizes. v

lAlthough the invention has been described as applied to a particularembodiment, it is in no way restrictedthereto and is' capable ofnumerous mo'dicationsand adaptations without departing from tlie scopeof the claims. -vr What is claimed is: l. In a telephone Yeii'cl'a'rigesystem, a plurality of operators cord circuits 'atan 'operatorsposition; a plurality of calling andcalled trunks ter-21 minating atsaid position, means for establishing a' connection from anycallin'gtrunk to any calledtrunk'over a cord, Va1ilurality of by-pass circuitsfor-said cord circuits,V iinders connected to eachl ley-pass circuit,said iiders being connected.

multiple to all said calling and called truhkslre=f spectiv'ely',` asequence switch for Veach bypass start relay adapted tobepperatedg-whenfagcord, interconnects certaintrunksr1-,herebymovingiindav ers associated with saidtrunks,-circuits-errergize'd upon operation ojf-saidstart relay forstarting and stopping the sequenceY :switch until the finders inconjunction with Athe, test relay g have'found thecalling and calledtrunks, and a talking circuit established-betweenthe callingl an`d=called trun-k-s' via an Vestablished by-passA circuit and'its Vassoci'ated finders.

of operators cord circuits atan'operator's 'posi-'- tion, aiplurality oftrunks terminating' in calling` and :called jacks, operators c'o'rdstoesta'blish a connection by means of a cord from '.anyjcalling eachby-pass circuit having lterminal banks'connected in multiple to allvsaid calling vand-'-'call'edl trunks respectively, a sequence switch.fori each byepass'circuit having two. normal positions l'andafplurality of operating positions, laV test'irelay 'forVv each iby-passcircuit, a start relay common toallv said by-pass circuits adapted to'beopera'tedwlien a cord interconnects certain trunks for starting theiirst'iinder of each pair of finders of all bypass circuits whosesequence vswitch is in either one of its two normal positions,anloperating circuit for each test` relay, the te`s`t relay circuit of aparticular by-pass circuit being closed upon the first finder thereoffinding the terminals of the calling trunk in said connection, saidcircuit including the last mentioned first finder, circuits controlledby the test relay for starting and stopping the sequence switch, therebycontrolling the hunting of the finders as the trunks are tested, anenergizing circuit closed for the test relay over the second finder whensaid second finder finds the terminals of the called trunk of saidconnection, means operative upon the last mentioned energization of thetest relay for moving the sequence switch into the next operatingposition in which the last mentioned finder is stopped. and a talkingconnection between the calling and called trunks in said connection viaan established byepass circuit and its associated pair of finders.

3. In a telephone exchange system, a plurality vof operators cordcircuits at an operators position, a plurality of calling and calledtrunks terminating at said position, detachable connectors at theoperators position for establishing a connection by means of a cord fromany calling trunk to any called trunk, a plurality of by-pass circuitseach terminating in a pair of finders for said cord circuits, the finderpair of each by-pass circuit having terminal banks connected in multipleto all said calling and called trunks respectively, a sequence switchfor each by-pass circuit having two normal positions and a plurality ofoperating positions, a test relay for each by-pass circuit, a startrelay commonV to all said by-pass circuits adapted to be operated when acord interconnects certain trunks and adapted to start the first linderof each pair of all by-pass circuits whose sequence switch is in eitherone of its two normal positions, an operating circuit for each testrelay the test relay operating circuit of a particular by-pass circuitbeing closed upon the first finder thereof finding the terminals of thecalling trunk in said connection, a circuit controlled by said testrelay for causing the associated sequence switch to move out of thenormal position occupied by it, means operative upon the sequence switchmoving out of itsnormal position for first stopping the asn e '2. In atelephone exchange'system, a'plurality Q.' sociatedirstnder.giseenuectugrthe .tstvrelev therefrom and stopping the huntingfirstiinders thenext operating positionof the sequeneefswitch forAstarting the second iindr: of the associated particular lley-passcircuit Aand forconnecting .the associated test `relay thereto anenergizing Acircuit closed `for the 'test relay over. thelast-rnentionedfinder -upon it iindingythe terminals, of the called trunk o ffsaidconnectionymeans operative .upon

the'second energization of the testjrelay adapted` tofmovethe-sequenceswitch into the next oper,-V

atingy position in which the last mentioned nder is stopped,;a talkingconnection between the calling andcalled trunks in said connection Vviathe particular by-pass circuit and its associatedgpair of-iinders, and-me'ans operative` upon the termination of -the conversation forreturning all the;

elements of the systemto normal.

4. -In atelephone exchangezsystein, a plural'v-ty of -operators cordcircuits at an operatorsv position, Va plurality of trunks`terminating-in callinga `sequencefswitch foreach by-lpass zcircuit,eachVV sequenceY switch having two normal positions anda plurality ofoperating positions, a test relay for each by-pass circuit, a startrelay common to all said by-pass circuits and adapted to be operatedwhen a cord interconnects certain trunks, said start relay when operatedbeing adapted to start the first nder of each pair of all by-passcircuits whose sequence switch is in either one of its two normalpositions, an operating circuit for each test relay, the test relayoperating circuit of a particular by-pass circuit being closed upon theirst finder thereof finding the terminals of the calling trunk in saidconnection, said circuit including the last mentioned first finder, a.circuit controlled by said test relay for causing the associatedsequence switch to move out of the normal position occupied by it, meansoperative upon the sequence switch moving out of its normal position forstopping the associated rst iinder, disconnecting the test relaytherefrom and then stopping the hunting first finders of all otherby-pass circuits,

a circuit closed in the next operating positions of the sequence switchfor starting the second iinder of the associated particular by-passcircuit and for connecting the associated test relay thereto, anenergizing circuit closed for the test relay over the last mentionedfinder upon it finding the terminals of the called trunk of saidconnection, means operative upon the second energization of the testrelay for causing the sequence switch to move into the next operatingposition in which the last-mentioned finder is stopped. and a talkingconnection established between the calling and called trunks in saidconnection via the particular by-pass circuit and its' pair ofassociated finders, means operative upon the termination of theconversation for moving the sequence switch of` the particular by-passcircuit into the next operating position, and means operated upon saidsequence switch being in said next operating position and adapted tomove the second finder engaged in the connection and the sequence switchof the particular by-pass circuit to normal positions.

f5: :In af telephone exchange system, a plurality` ofvoperators cordcircuits at an operators position, a plurality of'trunks terminating incalling and called jacks, operatorsV cords -to establish connectionsfrom'any calling trunk'jack to any` called trunk jack, a plurality ofby-pass circuits A1 each terminating in a pair of finders for said cordvcircuits, the finder pairo each by-pas's circuit having terminalbanksconnected in-multiple to all said calling and `called trunksrespectively. a

sequence switch for each by-pass circuit having two normal positions andal plurality of operating positions, a test relay for each oy-passcircuit, a

start relay common to all said by-pass circuitsthereof finding theterminals of the callingtrunk in said connection, said circuitincludingthe last mentioned first nder. a circuit controlled by Vsaidtest relay for causing the associated sequence switch to move out of thenormal position occupied by it, means operative upon the sequence switchhaving moved out of its normal position for stopping the associated rstnder, disconnecting the test relay therefrom and stopping the huntingfirst nders of all other by-pass circuits, a circuit closed in thenext'operating position of the sequence switch and adapted to start thesecond iinder of the particular by-pass circuit and to connect theassociated test relay to said last named second finder, an energizingcircuit for the test relayV closed over the last mentioned nder when itfinds the terminals of the called trunk of said connection, meansoperative upon the second energization of the test relay for Y movingthe sequence switch into the next'operating position in which the lastmentioned finder is f stopped, a talking connection established betweenthe calling and called trunks in said connection via the particularby-pass circuit and its pair of finders, means operative upon thetermination of i the conversation for moving the sequence switch of theparticular by-pass circuit into the nextV operating position, a circuitadapted to be closed 2:02 upon said sequence switch being insaid nextoperi ating position for operating the second nder of the particular.by-pass circuit engaged in the connection and returning it to normal,and a relay operated thereupon and adapted to move the aszb'r sociatedsequence switch into its next normal po-` sition. Y Y

- Y ANDRE JEAN HENQUET.

. ROGER MARCEL'MAUGEL No references cited,

